the Ores of Manganese. 139 



Pyrolusite is very often the product of decomposition of the 

 brachytypous parachrose-baryte, the carbonate of iron of the 

 latter being converted by the natural agents into the hydrate of 

 the peroxide, while the lime which it occasionally contains is de- 

 posited in the shape of calcareous spar or arragonite, and the 

 manganese is often found covering the surface of decomposed 

 rhombohedrons of the original species, in the shape of minute 

 crystals. In this manner it occurs in the mines of decomposed 

 sparry iron in beds in gneiss at Hiittenberg in Carinthia, at 

 Schmalkalden in Hessia, and other places. It is likewise found 

 in this manner in the counties of Sayn, Siegen, Salm and Hamm 

 in Prussia, in the veins of sparry iron traversing clay-slate, 

 which are decomposed in the upper levels, and then contain 

 much brown hematite. The localities are chiefly Friedewald 

 and Knorrenberg in the district of Kirchen, Sayn ; Streitberg 

 near the town of Siegen, and Horhausen and Herdorf, Siegen ; 

 Berge, Salm ; the mine Huth, near Hamm. One of the varie- 

 ties from Horhausen is particularly remarkable for the delicacy 

 of the fibres, which are disposed in small tufts within the geodes 

 of brown hematite, and which greatly resemble the fibrous varie- 

 ties of prismatoidal antimony-glance. There are specimens of it 

 in the imperial cabinet in Vienna, and in that of Mr Von STRUVE 

 in Hamburgh. Weyer in the county Wied-Runkel, Hirschberg 

 near Ahrensberg, and Bendorf on the Lower Rhine, are like- 

 wise named as the localities of superb specimens of pyrolusite. 

 Krettnich on the Blies, west of the Rhine, is likewise one of its 

 localities. Similar varieties occur in the iron mines of Bayreuth, 

 as at Armenhiilfe near Schnarchenreuth, and at Arzberg, in 

 those of Flatten, for instance Hilfe Gottes, and of Schwarzen- 

 thal in Bohemia, in those of Johanngeorgenstadt, Eubenstock, 

 Langenberg and others in Saxony, also at Reinerz in the county 

 of Glatz, and at Conradswaldau in Silesia. 



The finest crystals of pyrolusite occur at Schimmel and Oster- 



s2 



